It really depends on what definition of nationalism you’re using, absolutely. Original usage of “nationalism” had its meaning much closer to “patriotism”, the older of the two words, but usage over time has separated their definitions (again, dependant on where you are in the world).

In america “nationalism” is more often associated with ‘white nationalism’ and even when not explicitly tied to the white nationalist movement, ‘nationalism’ at best carries with it a negative connotation. “Nationalism” in the States means patriotism, but an exclusive sort which puts the rest of the world beneath the needs of America, even the basic needs of a given country’s right to self-determination if it goes against the US’s interests, which dovetails nicely with your definition of fanaticism